R – NHibernate and XML Serialization with IList

genericsnetnhibernatexmlxml-serialization

I've recently started using NHibernate, and on the whole like it a lot.

Until I ran into a problem with needing to serialize to XML and back.

I have a class that has a many to many relationship, so have an IList in the parent class to hold the list of child objects.

Class parentClass{
  IList<childClass> childList;

  string varA;
  string varB;
}

I need to be able to serialize this to XML and back, but obviously the IList prevents me from doing this, due to NHibernate wanting to control the concrete implementation of the IList, in this case using a Bag.

Ideally I want to avoid having separate DTOs just to replace the list, as my main motivation for using NHibernate was being able to use it with POCOs and not have to cook up a nasty framework around it.

I'm aware of being able to take control of the serialization process with ISerializable, but again that seems to negate the point of using NHibernate in the first place to reduce complexity.

Also the XML needs to remain 'plain' as it is used to inter-operate with third parties.

What's the best way to work around this constraint?

Thanks!

Best Answer

See:

C# Castle ActiveRecord: How to elegantly (XML) serialize ActiveRecord objects?

How do I serialize all properties of an NHibernate-mapped object?

NHibernate and WCF Serialization(Unidirectional)

JSON.NET and nHibernate Lazy Loading of Collections

Which .NET JSON serializers can deal with NHibernate proxy objects?

DTOs vs Serializing Persisted Entities

Returning NHibernate mapping classes from WCF services

Bottom line: use DTOs.

This is the style that Microsoft tends to use in their examples.

It appears that the guidance in this area may have changed, as StyleCop now enforces the use of the C# specific aliases.

C# – How to create an Excel (.XLS and .XLSX) file in C# without installing Microsoft Office

You can use a library called ExcelLibrary. It's a free, open source library posted on Google Code:

ExcelLibrary

This looks to be a port of the PHP ExcelWriter that you mentioned above. It will not write to the new .xlsx format yet, but they are working on adding that functionality in.

It's very simple, small and easy to use. Plus it has a DataSetHelper that lets you use DataSets and DataTables to easily work with Excel data.

ExcelLibrary seems to still only work for the older Excel format (.xls files), but may be adding support in the future for newer 2007/2010 formats.

You can also use EPPlus, which works only for Excel 2007/2010 format files (.xlsx files). There's also NPOI which works with both.

There are a few known bugs with each library as noted in the comments. In all, EPPlus seems to be the best choice as time goes on. It seems to be more actively updated and documented as well.

Also, as noted by @АртёмЦарионов below, EPPlus has support for Pivot Tables and ExcelLibrary may have some support (Pivot table issue in ExcelLibrary)

Here are a couple links for quick reference:
ExcelLibrary - GNU Lesser GPL
EPPlus - GNU (LGPL) - No longer maintained
EPPlus 5 - Polyform Noncommercial - Starting May 2020
NPOI - Apache License

Here some example code for ExcelLibrary:

Here is an example taking data from a database and creating a workbook from it. Note that the ExcelLibrary code is the single line at the bottom:

//Create the data set and table
DataSet ds = new DataSet("New_DataSet");
DataTable dt = new DataTable("New_DataTable");

//Set the locale for each
ds.Locale = System.Threading.Thread.CurrentThread.CurrentCulture;
dt.Locale = System.Threading.Thread.CurrentThread.CurrentCulture;

//Open a DB connection (in this example with OleDB)
OleDbConnection con = new OleDbConnection(dbConnectionString);
con.Open();

//Create a query and fill the data table with the data from the DB
string sql = "SELECT Whatever FROM MyDBTable;";
OleDbCommand cmd = new OleDbCommand(sql, con);
OleDbDataAdapter adptr = new OleDbDataAdapter();

adptr.SelectCommand = cmd;
adptr.Fill(dt);
con.Close();

//Add the table to the data set
ds.Tables.Add(dt);

//Here's the easy part. Create the Excel worksheet from the data set
ExcelLibrary.DataSetHelper.CreateWorkbook("MyExcelFile.xls", ds);

Creating the Excel file is as easy as that. You can also manually create Excel files, but the above functionality is what really impressed me.

Best Answer

Related Solutions

C# – the difference between String and string in C#

This is the style that Microsoft tends to use in their examples.

C# – How to create an Excel (.XLS and .XLSX) file in C# without installing Microsoft Office

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